Second thoughts about slab flattening setup.

[danceswithwindows]

I have been putting together a router slab flatting setup - like the ones where the you have a router mounted to a plate and it runs on rails (see photo).

I got a good quality 2 inch surfacing router bit. I have been doing some preliminary setup, and installed the bit with a 1/2” collet into my 2hp DW621.

With the bit installed, Im concerned I’m pushing the limits of what is safe with this router. I had to take the plastic dust collection piece off to get it in place, which is not a big deal I guess, I’m a little concerned at how close the edge of the bit is to the router baseplate/body. Of course it will be below this during milling, but nevertheless it catches the eye.

I’m also trying to figure out the best way to mount the router base to the plate that runs on the rails I have - doesn’t seem to be many great threaded screw holes in the base to work with.

Perhaps I am being overly cautious - I have not used such a big bit in my router before. Appreciate the thoughts or experiences you all may have.

 

[Echd]

As long as it's not hitting the sides of the guide and you're still evacuating chips - and I don't see why you wouldn't be- I wouldn't be overly concerned about the router and bit. You're going to take fairly light passes for the most part if you want a workable flatness with a router sled anyway, and you're going to overlap (with a cnc you'd call it "stepover") your passes to mitigate any visible marks from being out of dead flat.

I can't think of any reason you couldn't fab a mounting plate from wood to fit and use through bolts if necessary to secure everything, but I'd prefer an aluminum or steel mount.

 

[Woodman2k]

That bit is on the much side for a 2 hp router. It appears to be a variable speed motor so turn it down to the slowest speed possible. much like router arbor extensions, they magnify vibrations when extended. this bit will chatter the more you stick it out.Good Luck

 

[HMH]

My opinions - it’s definitely a big bit, but if you limit to light passes, (~1/16”-1/8” or so max?) I think it would be fine. If variable speed, I’d definitely considering turning it down a bit - that’s a lot of mass. Re: mounting, you could fab your own baseplate screwed to the body of the router as usual, perhaps out of lexan or similar, and use that to ride in a carriage of some sort.

 

[Wilsoncb]

As previously commenters said, lower your speed. You will soon know if your router has the torque to make it work at the lower speed. I don’t think it will make much difference if you stepped down to a 1-1/2” bit. Start with softer wood, shallow cuts and see how it goes.

I’m curious to see how it works out for you. I like the way DeWalt made a decent internal pocket for dust collection. I’m sure it won’t catch everything, but it looks like it should be better than most.

 

[mpeele]

Don't just lower you speed, set it to the lowest possible speed. Also take very shallow cuts. I can't tell from you picture because of the coating on the bit but I don't think you can plunge that bit, you have plunge off the material and then slide into the cut.

 

[Rwe2156]

And check the temp of the motor once in a while.

It’s really a job more suited to a 3 1/4HP router, but just be aware of heat. It’s not just the load, it’s how long the motor is running. Routers are not designed for continuous duty.

 

[awldune]

Wearing a face shield might be an idea if you are worried about things being thrown at you.

If the cutter were to touch the (presumably) cast aluminum of the router baseplate, I would expect it to chew up the baseplate with so little resistance that you wouldn't know it happened until you saw the metal chips.

 

[Ricksmi]

As others have said keep the speed of the router low preferably around 10000 but no higher than 15000 rpm, and take light passes which regardless of router size is the proper way to ensure a smooth cut, you should not have any issue.

 

[golfdad]

Where did you buy the rails and such

 

[Craptastic]

I'd have to 3rd or 4th the thought that router bit is a bit big for a 2hp router. I've used a couple of flattening rigs and it's always been my experience that you will certainly get better results with very light passes. Of more concern here though is your thought about being "overly cautious". I've never thought that to be a problem when dealing with a high rotational speed tool. Be extra cautious as much as you can muster up. Maybe (HOPEFULLY!) in the end everything ends up ok, but being safety conscious is how to keep your digits, limbs and life safeguarded for more future woodworking.

 

[chris_goris]

As per the mfr, 12-14k Rpms. max. that bit is designed for flattening mdf spoilboards on a CNC. I have one on my CNC and its seems happy at 12k Rpms. I dont push it hard using for flattening glue ups, max at about .090" depth per pass in hardwoods. The oYou need to run it buried in as far as it will go, to use it safely. This is one of the limitations of a handheld router and some sort of guide system with these larger cutters. They (cutters and handhled routers) simply arent designed to do this unfortunately. Good luck!.